Search results for "Coherence"

A framework for assessing frequency domain causality in physiological time series with instantaneous effects.

2013

We present an approach for the quantification of directional relations in multiple time series exhibiting significant zero-lag interactions. To overcome the limitations of the traditional multivariate autoregressive (MVAR) modelling of multiple series, we introduce an extended MVAR (eMVAR) framework allowing either exclusive consideration of time-lagged effects according to the classic notion of Granger causality, or consideration of combined instantaneous and lagged effects according to an extended causality definition. The spectral representation of the eMVAR model is exploited to derive novel frequency domain causality measures that generalize to the case of instantaneous effects the kno…

The Usefulness of Optical Coherence Tomography in Disease Progression Monitoring in Younger Patients with Relapsing-Remitting Multiple Sclerosis: A S…

2022

The purpose of the study was to assess the usefulness of optical coherence tomography (OCT) in the detection of the neurodegenerative process in younger patients with multiple sclerosis (MS). The study group consisted of 61 patients with a relapsing remitting course of MS (mean age 36.4 ± 6.7 years) divided into two groups: short (≤5 years) and long (>10 years) disease duration. OCT, P300 evoked potential, Montreal Cognitive Assessment, and performance subtests (Picture Completion and Digit Symbol) of the Wechsler Adult Intelligence Scale were performed in all patients. Mean values of most parameters assessed in OCT (pRNFL Total, pRNFL Inferior, pRNFL Superior, pRNFL Temporalis, mRNFL, G…

Two-Color Radiation Generated in a Seeded Free-Electron Laser with Two Electron Beams.

2015

We present the experimental evidence of the generation of coherent and statistically stable two-color free-electron laser radiation obtained by seeding an electron beam double peaked in energy with a laser pulse single spiked in frequency. The radiation presents two neat spectral lines, with time delay, frequency separation, and relative intensity that can be accurately controlled. The analysis of the emitted radiation shows a temporal coherence and a shot-to-shot regularity in frequency significantly enhanced with respect to the self-amplified spontaneous emission. © 2015 American Physical Society. © 2015 American Physical Society.

From interval-valued probability assessments to conditional probabilities with quasi additive classes of conditioning events

2005

Role of topological phase-defects in the parametric generation process

2008

Abstract We show that topological phase-defects are spontaneously generated from noise fluctuations in the degenerate configuration of the parametric interaction. These localized coherent structures are shown to affect the coherence properties of the parametrically generated field. It is shown that the emergence of coherence in the fundamental field relies on a previously unrecognized process of mutual annihilation of pairs of neighboring phase-defects. More precisely, the density of phase-defects N , and the time correlation τ c of the generated field, are shown to exhibit a power-law behavior with the propagation length, i.e., τ c ∝ z 1 / 4 , N ∝ z - 1 / 4 .

Everyday life in old age: past, present, and future

2018

Aims: To explore how older Norwegian women living at home experience ageing, and how their everyday life has been influenced by their encounters with the challenges of life. Methods: A qualitative design, interviewing ten women age 90 or older, was employed. Results: The overall theme of the findings is how everyday life in old age is influenced by past, present and future. The subcategories focus on (a) changes in daily life, (b) giving an account of life as it is, (c) various perceptions of experienced loss, and finally, (d) thoughts about the future. Conclusions: Older women need the opportunity to reflect upon their past, present and future existence to have a good everyday life in old …

Psychometric properties of Antonovsky's 29-item Sense of Coherence scale in research on older home-dwelling Norwegians.

2015

Aim: The aim of this study was to test the homogeneity and construct validity of the Sense of Coherence 29-item scale (SOC-29) among older home-dwelling Norwegians. Methods: A postal questionnaire, consisting of background variables, five health-related questions, the SOC-29, and three other instruments measuring mental health, self-care ability, and risk for undernutrition, was sent to 6033 home-dwelling older people (65+ years) in southern Norway. A total of 2069 participants were included. Homogeneity was assessed with Cronbach’s alpha coefficient and item-to-total correlations. The construct validity was assessed with “the known-groups technique,” a linear stepwise regression analysis …

Living alone, receiving help, helplessness, and inactivity are strongly related to risk of undernutrition among older home-dwelling people

2012

Solveig T Tomstad1, Ulrika Söderhamn2, Geir Arild Espnes3, Olle Söderhamn21Department of Social Work and Health Science, Faculty of Sciences and Technology Management, NTNU, Trondheim, Norway and Centre for Caring Research – Southern Norway, Faculty of Health and Sport Sciences, University of Agder, Grimstad, Norway; 2Centre for Caring Research – Southern Norway, Faculty of Health and Sport Sciences, University of Agder, Grimstad, Norway; 3Research Centre for Health Promotion and Resources HiST-NTNU, Department of Social Work and Health Science, Faculty of Social Sciences and Technology Management, NTNU, Trondheim, NorwayBackground: Being at risk of und…

On CPT Symmetry: Cosmological, Quantum-Gravitational and Other Possible Violations and Their Phenomenology

2004

I discuss various ways in which CPT symmetry may be violated, and their phenomenology in current or immediate future experimental facilities, both terrestrial and astrophysical. Specifically, I discuss first violations of CPT symmetry due to the impossibility of defining a scattering matrix as a consequence of the existence of microscopic or macroscopic space-time boundaries, such as Planck-scale Black-Hole (event) horizons, or cosmological horizons due to the presence of a (positive) cosmological constant in the Universe. Second, I discuss CPT violation due to breaking of Lorentz symmetry, which may characterize certain approaches to quantum gravity, and third, I describe models of CPT non…

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

2017

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, {\it narrow-band} analyses methods have been developed, allowing a fully coherent search for gravitational waves from known …